Measurement of transistors with a multimeter
Insert the pen in the same position as above; Its principle is the same as that of a diode. Assuming that pin A is the base, connect the black probe to that pin and the red probe to the other two pins respectively; If both readings are around 0.7V, then connect the red pen to pin A and the black pen to the other two pins. If both display "1", pin A is the base, otherwise it needs to be remeasured, and this transistor is a PNP transistor. So how to determine the collector and emitter? What should I do if a digital meter cannot use pointer swing to determine like a pointer meter? We can use the "hFE" gear to determine: first set the gear to "hFE", and you can see a row of small sockets next to the gear, which are used for measuring PNP and NPN tubes. The tube type has been determined earlier. Insert the base into the corresponding "b" hole of the tube type, and insert the other two pins into the "c" and "e" holes respectively. At this point, the value can be read, that is
β value; Fix the base again and swap the other two pins; Compare two readings, and the position of the pin with the larger reading corresponds to the surface "c" and "e".
Tip: The above method can only directly measure small tubes such as the 9000 series. To measure large tubes, the wiring method can be used, which involves using small wires to lead out the three pins. This makes it much more convenient.
Measurement of resistance
Insert the probe into the "COM" and "V Ω" holes, turn the knob to the desired range in "Ω", and connect the probe to the metal parts at both ends of the resistor.
be careful:
1. If the measured resistance value exceeds the maximum value of the selected range, an over range "1" will be displayed, and a higher range should be selected. For resistances greater than 1M Ω or higher, it takes a few seconds for the reading to stabilize, which is normal
2. When not connected properly, such as in an open circuit situation, the instrument panel displays "1"
3. When checking the impedance of the tested circuit, it is necessary to ensure that all power sources in the tested circuit are removed and all capacitors are discharged. If there are power sources and energy storage components in the tested circuit, it will affect the correctness of the circuit impedance test.
4. The 200M Ω gear of a multimeter has 10 words when short circuited. When measuring a resistance, these 10 words should be subtracted from the measurement reading. When measuring a resistance, it displays 101.0, and 10 words should be subtracted from 101.0. The actual resistance of the tested component is 100.0, which is 100M Ω.
5. During measurement, you can touch the resistor with your hand, but do not touch both ends of the resistor at the same time - the human body is a conductor with a large but limited resistance.
